Stoking this ill-feeling is the Liberal Democrats’ public negotiating strategy. Nick Clegg’s office has decided that it is imperative they show the public that they are fighting their corner in government, standing up for what they believe in. But to the Tories this is an immature way to do business. They complain that the Liberal Democrats’ megaphone diplomacy forces everyone to take public positions early and makes compromise impossible, turning coalition into a zero-sum game.

The Liberal Democrats are unapologetic about their new approach. For the first time in ages, they are enjoying themselves. It is as though the more they wind up the Tories, the more fun they have. They boast that they are making all the intellectual running on the Budget with their plans to cut taxes for low-paid workers by raising taxes on affluent savers. One senior Liberal Democrat remarks that this ‘might be the tail wagging the dog. But at least somebody is wagging something’.

This pre-Budget briefing is a particular source of Tory irritation. After all the leaks that surrounded last year’s autumn statement, the Tories secured an agreement to limit the number of people able to attend the most important meetings. This has been adhered to. But the Liberal Democrats are, to Downing Street’s fury, still using those known to be close to Clegg to make their Budget case.